The Science and Tradition of Tea Fermentation

Tea fermentation is a fundamental process in the history and culture of tea production, shaping the distinct flavors, aromas, and colors of various tea types. Fermentation, commonly referred to as oxidation, is a biochemical transformation in which enzymes within the tea leaves interact with oxygen, breaking down polyphenols and producing complex flavor compounds. This intricate process differentiates black, oolong, and pu-erh teas from their unoxidized counterparts like green and white teas.

The origins of tea fermentation date back thousands of years to ancient China, where early tea farmers inadvertently discovered the effects of oxidation when tea leaves were left exposed to air. Over time, these accidental discoveries evolved into refined techniques for crafting distinct tea varieties. The Chinese classification system identifies teas based on their degree of fermentation: green tea (unfermented), oolong tea (partially fermented), black tea (fully fermented), and post-fermented teas like pu-erh, which undergo microbial aging.

During the Tang Dynasty (618-907 CE), controlled fermentation techniques were established, allowing for greater consistency in tea production. The Song Dynasty (960-1279 CE) saw a surge in tea culture, leading to the development of specialized methods such as the steaming and rolling of leaves to preserve desired characteristics. By the Ming (1368-1644 CE) and Qing (1644-1912 CE) dynasties, fermentation processes were further refined, and new varieties, including pu-erh, gained prominence.

Beyond China, fermentation techniques spread to Japan, Korea, and the West. Japanese tea culture adapted methods to produce unique teas like matcha and sencha, focusing on minimal oxidation. Meanwhile, Korean teas, such as hwangcha, developed their own fermentation traditions. European traders in the 17th century fueled the demand for black tea, leading to large-scale production and innovation in oxidation control.

Modern advancements in fermentation leverage scientific research to optimize tea processing. Controlled environments, temperature regulation, and microbial cultures are now used to enhance specific flavors and health benefits. Recent studies highlight the probiotic potential of post-fermented teas, supporting gut health and immunity.

Tea fermentation remains a dynamic field, blending centuries-old traditions with modern innovation. As global interest in specialty teas grows, ongoing research continues to refine fermentation techniques, ensuring the preservation and enhancement of tea’s diverse flavors and cultural significance.
The Science and Tradition of Tea Fermentation

History of tea processing in India

In India, tea industry originated after 1823 as result of discovery of tea plant in Assam state. The tea was first discovered growing near Rangpur, now Sibsagar by Major Robert Bruce and his brother C.A. Bruce around AD 1823. The discovery led to the origins of the tea industry in India.

In the year 1834 Government of India formed a tea committee consisting of 12 members of whom 10 were Europeans and 2 Indians to explore possibilities of profitable tea cultivation in Assam.

Tea cultivation originally started in Darjeeling district of West Bengal during 1839 by Dr. Campbell, whereas it was spread in terai and duars region of West Bengal in 1862 and 1874 respectively.

In the early 1820s, the British East India Company began large-scale production of tea in Assam.

In 1837, the first English tea garden was established at Chabua in Upper Assam; in 1840, the Assam Tea Company began the commercial production of tea in the region and thereafter, the tea industry rapidly extended to other parts of the country.

In 1838 the first twelve chests of tea from Assam were received in England. On examination tea was found equally good with that of China.

Crush Tear and Curl (CTC) tea is more widely consumed than green tea. CTC teas generally produce a rich red-brown color when they are boiled by the Indian method. CTC tea manufacturing is the contribution of Sir William Mckercher, Superintendent of Amgoorie Tea Estate. He invented CTC machine in 1930. The CTC machine consists of two stainless steel engraved rollers with circumferential helical grooves.

Method of manufacturing CTC tea started gaining importance during 1950s. The process spread throughout India and Africa. In recent days, more than 85% of teas produced in West Bengal belong to this category.
History of tea processing in India

History of tea processing

The tea plant was first described taxonomically in 1753 by Carl Linnaeus in Species Plantarum. He referred to the tea plant as Thea and later refined the species into black tea (Thea bohea) and green tea (Thea viridis). By the early 1900s, taxonomists recognized that green and black tea were both from the same species, Camellia sinensis (L.) O. Kuntze.

According to the legend almost 5,000 years ago, the Chinese Emperor also renowned herbalist Shen Nung, was sitting under a tree while his servant boiled drinking water, when few leaves from the tree blew into it. The emperor was then attracted by the pleasant scent rising from the steaming infusion. Legend says the Emperor described a warm feeling as he drank the intriguing brew. The tree was a Camellia Sinensis, and the brew that was accidentally created was the tea beverage.

In the Eastern Jin Dynasty’s, tea trees had been planted in the gardens of the people of Ba shu and had been as tribute. Tea needs to be processed as a tribute, and the process is like sunbathing, Due to the role of light and heat, the quality has changed a lot. And it has a special flavor like the present white tea.

The cultivation, processing and preparation of green tea as a skilled practice and art developed in China during the 8th century by Buddhist monks, and was disseminated to the public by one monk in particular; Lu Yu, in The Classic of Tea.

Buddhist monks cultivated tea plants in and around their monastery gardens that they would harvest, process and drink during meditation and use as a tonic to maintain wellbeing. In the 12th century a Buddhist priest named Eisa brought tea seed from China to Japan. He may, therefore be cited as the founder of the Japanese tea industry.

Diversification of tea products expanded during the Ming Dynasty (1368 - 1644) in China when producers began to experiment with new processing techniques.

In the early 1600s, tea producers in the Wuyi Mountains began kneading the sun-withered tea leaves to macerate them, then allowed them to dry under the sun, thus reaching full oxidation and producing Gongfu black tea. It is acknowledged in China's tea circle that the place of origin of black tea and oolong tea is in Fujian. More specifically, Wuyi Mountain is considered as the origin by a majority of people.
History of tea processing